1. Field of the Invention
The present invention relates generally to a magnetic recording drive, a head slider of the magnetic recording drive, a manufacturing method of the head slider, and more particularly to a head slider operated according to a contact start stop (CSS) method, a magnetic recording drive in which the head slider can float over a surface of a magnetic recording medium, and a manufacturing method of the head slider.
2. Description of the Prior Art
In a magnetic disk apparatus, a flying head operated according to a contact start stop (CSS) method is adopted. In the CSS method, a magnetic head makes contact with a surface of a magnetic disk when the magnetic disk apparatus is not in operation. A head slider of the magnetic head is lifted up from the magnetic disk surface when the magnetic disk drive is in operation. Therefore, the head slider of the magnetic head slides over the magnetic disk surface when the disk stands and stops. In this case, a read-write magnetic head device is attached to the slider.
The head slider of the magnetic head flies over the magnetic disk surface due to an air flow on the magnetic disk surface generated by the rotation of the magnetic disk. The head slider flies according to a principle of a dynamic air pressure bearing at the magnetic disk surface.
To make the head slider fly, a convex portion, in which a floating force is generated by the air flow, is formed on a surface of the head slider facing the magnetic disk, and an air inflow region of the convex portion for the air flow is formed in a taper shape. The convex portion is generally called a rail surface (or a flying surface). The rail surface of the head slider makes contact with the magnetic disk surface before starting the operation of the magnetic disk or after stopping the operation of the magnetic disk. Therefore, to prevent wear and/or damage of the magnetic disk surface, a protective film made of a hard material such as carbon or the like is formed on a recording layer of the magnetic disk. In addition, a lubricant layer is formed on the protective film to reduce friction and wear of the protective film. Therefore, the durability of the protective film is improved.
Also, as the magnetic disk drive is downsized and information is recorded in a higher recording density in the recording disk, a flying height (or a space) between the magnetic head and the magnetic disk is intended to be lowered. To lower the flying height, it is required to suppress the roughness of the magnetic disk surface as small as possible to prevent an undesirable contact of the magnetic head set in a flying condition with the magnetic disk.
However, when the magnetic disk is rest in a stop condition, a contact area of the magnetic disk with the head slider becomes larger as the magnetic disk surface becomes smooth. Therefore, stiction (or adhesion) of the head slider to the magnetic disk easily occurs, and a strength of the stiction increases. Because of the increase of the strength of the stiction, a load required to start rotating the magnetic disk increases. In this case, because a torque of a spindle motor for rotating the magnetic disk is decreased as the magnetic disk apparatus are downsized, there is a case that the magnetic disk cannot be rotated because of the weakness of the torque. Also, the suspension for supporting the head slider, is easily damaged and broken when the rotation of the magnetic disk is started.
To suppress the stiction, an idea that a head slider flying surface facing the magnetic disk is crown-processed along its longitudinal direction and decrease a contact area of the head slider with the magnetic disk is proposed. However, though the head slider formed in a crown shape is effective to prevent the stiction, it is difficult to form a large number of head sliders in the crown shape with the tight accuracy for mass production. Also, because the head slider is crown-processed along its longitudinal direction, a distance between a magnetic transducer arranged on an air outflow end side of the convex portion and the magnetic disk surface becomes larger than that between the rail surface and the magnetic disk surface. Therefore, there is a drawback that a spacing loss occurs.
Also, to suppress the stiction, an idea that projections are provided on rail surfaces (or an air bearing surface) of the head slider facing the magnetic disk to decrease a contact area of the magnetic disk with the head slider is, for example, disclosed in the Published Unexamined Japanese Patent Application (PUJPA) No.S51-71117.
Recently, the flying height is equal to or less than 100 nm. Therefore, it is difficult to precisely adjust a height of the projection by controlling an etching time required to etch the rail surface, and there is a drawback that a yield rate of the projection is lowered. Also, it is required to accurately adjust the height of the projection to improve a stable operation of the magnetic disk apparatus when the flying of the head slider is started or stopped.
The whole weight of the head slider loads onto projections having small surfaces. This causes large friction of the projection surfaces on the disk surface. As a result, the projections wear out rapidly.
Also, even though a plurality of projections are provided on the head slider, when the number of projections is decreased to reduce the contact area, a contact pressure at the contact area of the projections is increased, and there is a case that the lubricant layer of the magnetic disk is worn away. As a result, a solid-to-solid contact area is increased, and the surfaces of the projections and the magnetic disk are worn because of friction between the projections and the magnetic disk. Also, the stiction between the projections and the magnetic disk is increased, and the reliability for operating the head slider is lowered.